1. Field of the Invention
This invention relates to equipment for removing one layer of liquid floating on top of second layer of liquid, such as an oil or petroleum slick floating on a bodies of water, such as rivers, lakes, harbors, and even the open sea. More particularly, the invention relates to oil spill clean-up equipment which utilizes a floating barrier that is used to both surround the spill, or a portion of it, and remove oil from the spill at the surrounded edges thereof.
2. Description of the Prior Art
The Industrial Revolution, which began around 1750, created an almost insatiable demand for energy. In 1776, the same year that the American colonists declared independence from Great Britain, a Scottish engineer named James Watt designed an improved steam engine having a separate condenser, thereby eliminating the need to periodically cool the engine""s cylinder. Though first used to drive mine pumps, Watt""s steam engines soon found use in textile factories. From that time until the beginning of the twentieth century, the Industrial Revolution was powered primarily by steam engines fueled with coal. Around 1870, the internal combustion engine was developed. Lighter, more compact and more efficient than the steam engine, the internal combustion engine gradually displaced the steam engine which, in developed countries, had virtually disappeared from industrial use by 1960. Turbine engines came into wide use in the late 1950s as powerplants for both aircraft and electric generators. During World War II, the need for synthetic polymers to replace scarce naturally-occurring polymers such as natural rubber and silk spawned the rapid development of the petrochemical industry. At the beginning of the twenty-first century, the world is continuing to squander its petroleum reserves, from which most liquid fuels and most synthetic polymers are derived.
The profligate use of petroleum products is not without costs. There is increasing evidence that the global warming is largely attributable to the combustion of fossil fuels. In addition, the exploitation of petroleum reserves, which first requires exploration and drilling; later requires pumping, transportation, and refining of the crude; and finally requires transportation and marketing of the refined products, exacts its own environmental damage. The most serious environmental damage is almost certainly caused by the leakage of crude petroleum from tanker ships with damaged hulls and from broken pipes on offshore oil wells into the ocean. Super tanker ships capable of transporting several hundred thousand tons of crude petroleum are in widespread use and pose a serious threat to ocean environments. Leakage from broken pipes which transport crude petroleum across ecologically fragile regions on land can also create environmental havoc.
As the density of petroleum products is about eighty percent that of water, crude petroleum and petroleum products float on water. In the absence of an emulsifying agent, petroleum products are generally not miscible with water. These physical properties make possible the near complete recovery of petroleum products spilled onto bodies of water if the spill is rapidly contained, storms do not widely disperse the oil slick, and the spill occurs far enough from shore that it is not washed up on beaches before containment is effected. Without question, the more rapidly an oil spill can be contained, the greater the likelihood that the cleanup effort will be effective and environmental damage will be minimized. Thus, the speed with which an oil recovery system can be deployed is at least as important as its effectiveness in skimming the spilled oil from the body of water.
Much equipment has been developed for recovering layers of petroleum products floating on water. One such apparatus is disclosed in U.S. Pat. No. 3,221,884 to Jacques Muller. The apparatus includes a pair of parallel buoyant pipes, the first of which has inlets which admit water and oil mixture from an oil spill into the pipe, which conducts the mixture to suction pump on a ship, the second pipe having outlets to discharge water from which oil has been removed. The buoyant pipes are interconnected by a series of spaced-apart spacer bars, which support a third pipe used to provide ballast for the pair of buoyant pipes to that the inlets of the first buoyant pipe are positioned at a level that will admit primarily oil from the oil spill.
A floatable collar for confining oil spills is disclosed by U.S. Pat. No. 3,369,664 to Paul C. Dahan. The collar comprises an inflatable tube having a weighted skirt attached thereto below the inflatable tube and bulwark made semirigid by inflatable means located above the inflatable tube.
The oil slick confinement apparatus disclosed in U.S. Pat. No. 3,565,254 to John P. Latimer includes a vertically-oriented dam attached to a buoyancy member. A awning member, which extends the length of the dam, includes a floating lower edge which rides lightly on the spill side of the dam. The awning member also includes a air suction pipe which maintains pressure between the dam and awning at less than atmospheric. A floating oil collection pipe beneath the awning, which also extends the length of the dam, has inlets through which oil can be suctioned from the spill and transported to a ship or barge for collection.
Another apparatus for gathering a floating layer of oil from a body of water is disclosed by U.S. Pat. No. 3,584,462 to Phillip S. Gadd. An impermeable barrier is suspended within screened enclosure of U-shaped cross section. One embodiment of the apparatus employs a barrier suspended along both edges to form a trough through which oil might be transported to a collection location.
Another buoyant oil confinement boom is disclosed by U.S. Pat. No. 3,666,098 to Charles Garland, et al. The boom, which is primarily a floating pipe having perforations to receive oil from a spill, includes a suction pump coupled to one end thereof, and a skirt that is dependingly attached to the pipe so that it extends over the perforations without blocking them.
Yet another oil control boom is disclosed by U.S. Pat. No. 4,752,393 to Frank Meyers. This boom has walls which define an elongated hollow flotation chamber. Apertures in the walls of the chamber, admit oil, water, or a mixture of both into the chamber, from whence it is removed by a pump for removal of the oil.
An oil containment boom and skimmer is disclosed by U.S. Pat. No. 5,160,432 to Peter Gattuso. A first longitudinally extending tubular member is placed adjacent to the oil spill area. It includes an inner open area and inlets for receiving oil and water. A second longitudinally extending tubular member is placed parallel to the first member. A passageway with a lip connects the members and is placed slightly above sea level for skimming the upper layer of oil.
An oil spill containment and recovery system is disclosed by U.S. Pat. No. 5,533,832 to Howard Dugger. The system includes multiple containment float/recovery trough sections for collecting spilled petroleum from the water""s surface. The water and petroleum mixture is transferred from the collection trough by a pump to a separation tank.
The present invention provides an oil recovery system that includes a floating containment boom having an adjustable height internal oil skimmer for improved oil skimming efficiency. The boom is preferably of sufficient length to surround the spill, or a least a portion thereof. The boom includes an outer pipe that is longitudinally perforated on one side that is placed against a spill. The outer pipe is equipped with flotation devices, the buoyancy of at least one of which is adjustable. The adjustable buoyancy allows the boom to be floated at an optimum level. The boom also includes an inner pipe that is also longitudinally perforated on a single side, the inner pipe being generally coextensive with the outer pipe and rotatably positioned in support members within the outer pipe. Both the outer and inner pipe may be assembled from shorter sections joinable with couplings. The flotation devices may be incorporated into the couplings.
For a preferred embodiment of the invention, the outer and inner pipes are non-concentrically positioned with respect to one another, with inner pipe supports immovably positioned within the outer pipe. The supports position the inner pipe near the upper inner surface of the outer pipe and permit the inner pipe to be rotated so that the level of the perforations in the inner pipe may be adjusted within the chamber of the outer pipe. A minimum of two suction pumps are employed in conjunction with the boom: a first pump to draw a water and oil mixture into the outer pipe; a second pump to draw primarily oil into the inner pipe. The water and oil mixture removed from the outer pipe by the first pump is returned to the spill area. Oil mixed with some water withdrawn from the inner pipe by the second pump is sent to a separator located on a ship, barge or the shore. Oil is stored for subsequent use and the clean water separated therefrom is returned to a unpolluted area of the body of water.
In order to accurately adjust the level of the perforations on the inner pipe, the end thereof is equipped with an external circumferential straight-cut gear. A bell rotatable about the end of the outer pipe incorporates an internal circumferential straight-cut gear that meshes with the external gear on the inner pipe. As the bell is rotated about the outer pipe, the inner pipe also rotates. The bell may be equipped with stops to arrest its revolution about the outer pipe, thereby setting the inner pipe at a desired rotational position.